Form for concrete slabs



May 11, 1965 E. R. LAWRENCE.

FORM FOR CONCRETE SLABS Filed Aug. 2, 1962 n. n inv/1l H K f.. 7 ,E ...fa w. pw w 1x 7 5% .94 4 1:1 j .J a a J f 4 ,a .f N u M y l... www 4 a xEB f l .wf y. u

United States Patent O 3,182,948 FGRM FOR CONCRETE SLABS Earnest RalphLawrence, 5684 Peggy Lane, Arlington, Calif. Filed Aug. 2, 1962, Ser.No. 214,412 14 Claims. (Cl. 249-18) The present invention relatesgenerally to sectional steel forms for the production of concrete slabsin a horizontal position, and more particularly to sectional forms forcasting concrete structural walls in a horizontal position from whichthey may be tilted upwardly to form a walled structure.

In the formation of reinforced concrete walls for buildings, the tilt-upmethod of construction casts the walls horizontally where they are to beerected. Suitable hooks or other anchor means may be inserted and castwithin the slab to enable a crane or other structural apparatus to liftthe precast slab int-o position as a vertical Wall after the concretehas solidified. In this method of construction it is apparent that theconcrete slab may be precast with only side building forms whosevertical height need be equal only to the thickness of the slab. Thisresults in a much more simplified form than would be required if thewalls were cast in vertical position, and does away with the bracingwhich is required for a vertically cast wall.

Itis, therefore, an object of the present invention to provide animproved building form construction for the casting of horizontalreinforced concrete slabs.

Another object of this invention is an improved building form for thecasting of horizontal concrete slabs having provision for increasing thevertical height of the forms to increase the thickness of the cast slab.

A further object of the present invention is the provision of animproved building form construction for casting horizontal concreteslabs in which forms may be stacked vertically to provide for thecasting of additional slabs upon the platform provided by the uppersurface of a lower cast concrete slab.

Yet another object ofv this invention is the provision of improvedbuilding forms for the casting of horizontal reinforced concrete slabsin which the forms may be stacked vertically to provide any desired formheight and in which the stacked forms have improved means for holdingand pulling the forms together to give the stack greater vertical andhorizontal stability.

A still further object of this invention is the provision of a buildingform construction for casting horizontal concrete slabs having improvedarrangements for sectionalizing and supporting the forms and forsupporting reinforcing bars thereon.

These and other objects and features of the invention will be readilyapparent to those skilled in the art from the following specificationand the appended drawing illustrating a presently preferred embodimentthereof, in which:

FIGURE 1 is a broken perspective view of a building form constructionaccording to the present invention with a concrete slab cast therein;

FIGURE 2 is a horizontal sectional view of a joint between sections ofthe building form;

FIGURE 3 is a vertical sectional view through vertically stackedbuilding forms according to the present invention;

FIGURE 4 is a detail horizontal sectional view on the line 4-4 of FIGURE3;

FIGURE 5 is a perspective view showing the connecting and supportingmeans for the sections of the upper level of the stacked building formsof VFIGURE 3; and

ice

FIGURE 6 is a perspective view of a key for tying and pulling thestacked forms together.

The precast concrete slab form acc-Ording to the present invention isindicated generally at 11, and is sectional in construction, being builtup of corner end sections 12 and intermediate section 13. The endsections 12 extend for the the full vertical height of the form, whilethe intermediate sections 13 extend for less than one-half the verticalheight of the form and are spaced apart at the mid horizontal plane toprovide a slot 14 therebetween. Reinforcing bars 15 extend transverselyacross the opening between the sides of the form and have their endsreceived in the slot 14 in supported relation.

The end sections 12 are formed of sheet metal and have vertical walls 16extending the height of the form with integral, outwardly extendinghorizontal flanges 17 and 18 at the top and bottom thereof,respectively. Rigid attachment plates 19 are rigidly secured, as bywelding, to the outside surfaces of the vertical walls 16 adjacent theopposite ends thereof.

The intermediate sections 13 are formed of sheet metal and have verticalwalls 21 provided with integral, outwardly extending horizontal flanges22 and 23 at the top and bottom thereof. The superposed intermediatesections 13 are spaced apart, as stated hereinbefore, to provide theslot 14 between the lower ange 23 on the upper section andthe upper ange22 on the lower section. Rigid attachment plates 24 are welded orotherwise secured to the outside surfaces of the vertical walls 21adjacent the opposite ends of the sections 13.

Supports 30 for joining the intermediate form sections together and tothe end sections and for bracing the assembled form may be seen moreparticularly in FIGURES l and 2. Each support 30 comprises a horizontalbase plate 31 to which are welded a pair of vertically extending angles32 and 33 having their opposed legs 34 and 35, respectively, spacedapart to provide a slot 36 therebetween. Vertically spaced straps 39 and41 are rigidly mounted, as by welding, to the inwardly facing legs 37and 38 of the angles 32 and 33. The ends of straps 39 and 41 formattachment ears and are provided with slots 42 therethrough. Studs 43extend through the slots 42 and -are screwed into threaded openings 44in the plates 24 -horizontally extending slot 14. By this means theintermediate sections 13 are rigidly secured together and to theconnecting support which, in turn, by its base plate 31, holds theassembled form sections erect against the force exerted by the concretepoured therein. The adjacent ends of the end sections 12 are alsoconnected to supports 30. The corner ends of the end sections 12 may bejoined together by angles 51 to whose opposite legs the plates 19 aresecured, as by studs 53 which pass through slots 54 in the legs of theangles and are screwed into threaded openings in the plates 19. i

To increase the height of the building form, additional upper endsections 12 may be stacked on the lower end sections 12, and additionalupper intermediate sections 13 may be stacked above the lowerintermediate sections 13, the latter arrangement being shown in thevertical section of FIGURE 3. The upper end sections 12 may be connectedtogether at the corners by means of angles 51. At points intermediatethe corners, the form sections may be joined together by connections 61,FIGURE 5, which also serve to tie and draw together the upper and lowerlevels of the stacked forms.

Each connector 61 includes a pair of angles 62 and 63, which may beidentical with the lower angles 32 and 33.

Across the angles 62 and e3 are mounted connecting straps 64 and 65,which may be identical with the straps 39 and 41 and which are likewisesupplied with slots 66 through which extend studs 67 threaded into theplates 2.4 on the upper level section 13. Between the legs 67 and 68 ofthe angles 62 and 63 is rigidly secured a depending tongue 69 whichextends into the slot 36 between the legs 34 and 3S, as shown in FIGURES3 and 4. The tongue 69 has an angle slot 71 therein in alignment withangle slots '72 and 73 in the legs 34 and 35 when the form sections areproperly arranged in stacked relation. A locking wedge-shaped key 75 isshown in perspective in FIGURE 6, and in locking position in FIGURE 4,and has an angular cross section which conforms to the configurationofthe slots 71, 72 and 73, so that as the wedge-shaped key is driveninto position, as shown in FIGURE 4, it will draw the upper and lowerlevels of the form together to give greater vertical and horizontalstability to the stacked form sections.

Where the forms are stacked, as in FIGURE 3, they can, of course, beused in any desired number of levels, two only being shown in thisfigure. Also, the slabs may be cast as a single slab of increasedthickness; or a bondbreaking agent at 76 may be applied between thelevels so as to produce successive slabs of the same original height bycasting an upper slab upon the upper surface of the lower slab used as aplatform.

The lower concrete slab may be cast directly on the ground, or on aplatform 77 which may be rigid or in the form of building paper orsimilar material spread upon the ground; similarly, the bond-breakingagent 76 can be building paper or a powdered or paste material spread onthe upper surface of the lower slab.

The slot 14 between the ends of the reinforcing bars 1S may be filled,if desired, with any material to prevent the fluid concrete oozingtherethrough; for example, a simple expedient is building paper on theinside surface, bridging the slot. Where the slot is narrow, no pluggingmeans may be required if the poured concrete is sufficiently thick.

The manner of assembling the building form according to the presentinvention will be obvious from the above description, the intermediatesections being connected together and to one end of the end sections bymeans of the intermediate supports 30, while the end sections areconnected together at the corners by means of the angles 51. Thereinforcing rods 15 may be inserted through the slots 14, either afterassembly or may be placed on the flanges 22 prior to mounting of theupper sections 13. Where the slab of precast reinforced concrete is toform a building wall, suitable hooks or anchor means may be insertedthrough the slot 14 at what is to be the top edge of the wall and, afterthe concrete has solidified and the forms 12 and 13 removed, a crane orother structural apparatus may be attached to these hooks and the slabtilted or raised into the vertical position and secured in place as astructural building wall. It will be understood, of course, that theform according to the present invention is not limited to the casting ofbuilding wall slabs, nor to walls used in a tilt-up method of buildingconstruction; but is usable for the casting of horizontal concrete slabsgenerally.

Where thicker slabs are desired, or where it is desired to cast a secondslab upon a lower slab as a platform, the stacked construction ofFIGURES 3 through 5 is utilized. Here the upper intermediate sectionsare connected together and to the adjacent ends of the end sections bythe supports 61 of FIGURE 5, with the tongues 69 extending into theslots 36 between the legs 34 and 35 of the lower level connectors 30,and with the upper and lower levels pulled together and tied by thewedge-shaped key '75 extending through the aligned slots 7l, 72 and 73.Where individual slabs are to be cast, with the lower slab used as theplatform, a bond-breaking agent is used between the slabs as at 76.

After the concrete has solidified, the form sections are lreadilydisassembled after first removing the bolts 43 and 53 and, where stackedlevels are used, after removal of the keys by driving them in reversedirection out of the slots 71-73.

While a certain preferred embodiment of the invention has beenspecifically illustrated and described, it will be understood that theinvention is not limited thereto, as many variations will be apparent tothose skilled in the art, and the invention is to be given its broadestinterpretation within the terms of the following claims.

I claim:

l. A form for casting a concrete slab in horizontal position comprising:a plurality of form sections; and means connecting said sectionstogether in substantially end-toend relation to define a verticallyenclosed volume of small height relative to its horizontal dimensioncorrespending to the slab to be cast therein, said form sectionsincluding corner end sections having substantially continuous verticalwalls and intermediate sections having interrupted vertical wallsproviding horizontal slots in substantially the mid horizontal plane ofthe form for receiving and supporting the ends of slab reinforcing rodsextending in the plane of the slab between sections at opposite sides ofthe form.

2. A form -for casting a concrete slab in horizontal positioncomprising: a plurality of form sections; and means connecting saidsections together in substantially end-to-end relation to define avertically enclosed volume of small height relative to its horizontaldimensions corresponding to the slab to be cast therein, said formsections including corner end sections having substantially continuousvertical walls and intermediate sections having interrupted verticalwalls providing horizontal slots in substantially the mid horizontalplane of the form for receiving and supporting the ends of slabreinforcing rods extending in the plane of the slab between sections atopposite sides of the form, said corner end sections `being in the formof U-shaped channels providing outwardly extending horizontal flanges atthe top and bottom thereof, :and said intermediate secions havingoutwardly extending horizontal flanges at the top and bottom thereof andat opposite sides of said slot.

3. A form `for casting a concrete slab in horizontal positioncomprising: a plurality of form sections; and means connecting saidsections together in substantially end-to-end relation to define avertically enclosed volume `of small height relative to its horizontaldimensions corresponding to the slab to be cast therein, said formsections including corner end sections having substantially continuousvertical walls and intermediate sections having interrupted verticalwalls providing horizontal slots for receiving and supporting the endsof slab reinforcing rods extending in the plane of the slab betweensections at opposite sides of the form, said corner end sections beingin the `form U-shaped channels providing outwardly extending horizontalflanges at the top and bottom thereof, said intermediate sectionscomprising superposed section portions spaced vertically to provide saidhorizontal slots, each section portion being a substantially U-shapedchannel having outwardly extending horizontal flanges at the top andbottom of the portion.

4. A form for casting a concrete slab in horizontal position comprising:a plurality of form sections; and means connecting said sectionstogether in substantially end-toend relation to define a verticallyenclosed volume of small height relative to its horizontal dimensionscorresponding to the slab to be cast therein, said connecting meanscomprising horizontal base plates, supports extending vertically fromsaid base plates, and attachment means extending transversely of saidVertical supports and permanently mounted thereon and having meansadjacent their opposite ends for atachment to the adjacent ends of saidsections, said form sections including corner end sections havingsubstantially continuous vertical walls and intermediate sections havinginterrupted vertical walls providing horizontal slots for receiving andsupporting the ends of slab reinforcing rods extending in the plane ofthe lab between sections at opposite sides of the form.

5. A form for casting a concrete slab in horizont-al positioncomprising: a plurality of form sections; and means connecting saidsections together in substantially end-to-end relation to define avertically enclosed volume corresponding to the slab to be cast therein,said connecting means comprising horizontal base plates, supportsextending vertically from said base plates, and attachment meansextending transversely of said vertical supports and having meansadjacent their opposite ends for attachment to the adjacent ends of saidsections, said vertical supp-Orts each comprising a pair of verticallyextending angles having oppositely extending, inwardly facing legs onwhich said attachment means are mounted and adjacent, outwardlyextending legs spaced apart to provide a slot therebetween for thereception of an attachment tongue.

6. A form for casting a concrete slab in horizontal position comprising:a plurality of form sections; and means connecting said sectionstogether in substantially end-to-end relation to define a verticallyenclosed volume corresponding to the slab to be cast therein, saidconnecting means comprising horizontal base plates, supports extendingvertically from said base plates, and attachment means extendingtransversely of said vertical supports and having means adjacent theiropposite ends for attachment to the -adjacent ends of said sections,said vertical supports each comprising a pair of vertically extendingangles having oppositely extending, inwardly facing legs on which saidattachment means are mounted and adjacent, outwardly extending legsspaced apart to provide a slot therebetween for the reception of anattachment tongue, said form sections including corner end sectionshaving substantially continuous vertical walls and intermediate sectionshaving interrupted vertical walls yproviding horizontal slots forreceiving and supporting the ends of reinforcing rods extending betweensections at opposite sides of the form.

7. A form for casting a concrete slab in horizontal position comprising:a plurality of form sections; means,

connecting said sections together in substantially end-toend relation todefine a vertically enclosed volume corresponding to the slab to =becast therein, said connecting means comprising horizontal base plates,supports extending vertically from said base plates, and attachmentmeans extending transversely of said vertical supports and having meansadjacent their opposite ends for attachment to the adjacent ends of saidsections, said form sections including corner end sections in the formU- shaped sheet metal channels providing outwardly extending horizontalflanges at the top and bottom thereof and intermediate sectionscomprising superposed section portions spaced vertically to providehorizontal slots therebetween, each section portion being asubstantially U-shaped sheet metal channel providing outwardly extendinganges at the top and bottom of the portion; and heavy attachment platesrigidly secured to the outside surfaces of the -sections and sectionportions adjacent the ends thereof and between said flanges, by whichconnections to the'sections are made.

8. A multiple level form for casting a concrete slab in horizontalposition comprising: a rst level form including a plurality of formsections; means connecting said sections together in substantiallyend-to-end relation to define a vertically enclosed volume correspondingt0 the slab to be cast therein, said connecting means comprisinghorizontal base plates, supports extending vertically from said baseplates, and attachment means extending transversely of said verticalsupports and having means adjacent their opposite ends for attachment tothe adjacent ends of said sections, said vertical supports eachcomprising a pair of vertically extending angles having oppositelyextending, inwardly facing legs on which said attachment means aremounted and adjacent, outwardly extending legs spaced apart to provide aslot therebetween; a second level form mounted above said first levelform and comprised of sections substantially duplicating the sections ofsaid first level form, said second level sections being connectedtogether in substantially end-to-end relation to define a secondvertically enclosed volume a substantially duplicate Iof said firstenclosed volume and located immediately above the same, the meansconnecting the second level sections together including a dependingvertical tongue disposed -within the slot between said outwardlyextending angle legs; substantially aligned slots in said tongue andspaced angle legs; and a wedge-shaped key insertable through said slotsto draw said upper level sections down to said lower sections and tiethe two levels together.

9. A multiple level form for casting a concrete slab in horizontalposition comprising: a rst level form including a plurality of formsections; means connecting said sections together in substantiallyend-to-end relation to define a vertically enclosed volume correspondingto the slab to be cast therein, said connecting means comprisinghorizontal base plates, supports extending vertically from said baseplates, and attachment means extending transversely of said verticalsupports and having means adjacent their opposite ends for attachment tothe adjacent ends of said sections, said vertical supports eachcomprising a pair of vertically extending angles having oppositelyextending, inwardly facing legs on which said attachment means aremounted and adjacent, outwardly extending legs spaced apart to provide aslot therebetween, said form sections including corner end sectionshaving substantially continuous vertical walls and intermediate sectionshaving interrupted vertical walls providing horizontal slots forreceiving and supporting the ends of reinforcing rods extending betweensections at opposite sides of the form; a second level form mountedabove said first level form and comprised of sections substantiallyduplicating the sections of said first level form, said second levelsections being connected together in substantially end-to-end relationto define a second vertically enclosed volume a substantially duplicateof said first enclosed volume and located immediately above the same,the means connecting the upper level sections together including adepending vertical tongue disposed within the slot between saidoutwardly extending angle legs; substantially aligned slots in saidtongue and spaced angle legs; and a wedgeshaped key insertable throughsaid slots to draw said upper level sections down to said lower sectionsand tie the two levels together.

l0. A multiple level form for casting a concrete slab in horizontalposition comprising: a first level form including a plurality of formsections; means connecting said sections together in substantiallyend-to-end relation to define a vertically enclosed volume correspondingto theslab to be cast therein, said connecting means comprisinghorizontal base plates, supports extending vertically from said baseplates, and attachment means extending transversely of said verticalsupports and having means adjacent their opposite ends for attachment tothe adjacent ends of said sections, said vertical supports eachcomprising a pair of vertically extending angles having oppositelyextending, inwardly facing legs on which said attachment means aremounted and adjacent, outwardly extending legs spaced apart to provide aslot therebetween, said form sections including corner end sectionshaving substantially continuous vertical Walls and intermediate sectionshaving interrupted vertical walls providing horizontal slots forreceiving and supporting the ends of reinforcing rods extending betweensections at opposite sides of the form; a second level form mountedabove said first level form and comprised of sections substantiallyduplicating the sections of said first level form, said second levelsections being connected together in substantially end-to-end relationto define a second vertically enclosed volume a substantially duplicateof said first enclosed volume and Y located imediately above the same,the means connecting the upper level sections together including adepending vertical tongue disposed within the slot between saidoutwardly extending angle legs; substantially aligned slots in saidtongue and spaced angle legs; and a wedgeshaped key insertable throughsaid slots to draw said upper level sections down to said lower sectionsand tie the two levels together, said slots being shaped substantiallyas right angles and said wedge-shaped key having substantially a rightangle cross section complementary to the shape of said slots.

11. A multiple level form for casting a concrete slab in horizontalposition comprising: a first level form including a plurality of formsections; means connecting said sections together in substantiallyend-to-end relation to define a vertically enclosed volume correspondingto the slab to be cast therein, said connecting means comprisinghorizontal base plates, supports extending vertically from said baseplates, and attachment means extending transversely of said verticalsupports and having means adjacent their opposite ends for attachment tothe adjacent ends of said sections, said vertical supports eachcomprising a pair of vertically extending angles having oppositelyextending, inwardly facing legs on which said attachment means aremounted and adjacent, outwardly extending legs spaced apart to provide aslot therebetween, said form sections including corner end sectionshaving substantially continuous vertical walls and intermediate sectionshaving interrupted vertical walls providing horizontal slots forreceiving and supporting the ends of reinforcing rods extending betweensections at opposite sides of the form; a second level form mountedabove said first level form and comprised of sections substantiallyduplicating the sections of said first level form, said second levelsections being connected together in substantially end-to-end relationto define a second vertically enclosed volume a substantially duplicateof said first enclosed volume and located immediately above the same,the means connecting the upper level sections together including adepending vertical tongue disposed within the slot between saidoutwardly extending angle legs; substantially aligned slots in saidtongue and spaced angle legs; a wedge-shaped key insertable through saidslots to draw said upper level sections down to said lower sections andtie the two levels together, said upper level connecting means eachcomprising a pair of vertically extending angles having oppositelydirected, inwardly facing legs and outwardly directed legs spaced apartto form a slot therebetween; and attachment means for the ends of saidupper level sections secured to said upper level inwardly facing anglelegs and having means at the opposite ends thereof for attachment to thesection ends,

said tongue being rigidly mounted in mounted in the lower portion of theslot between said upper level spaced angle legs.

12. Structural supporting means for the narrow vertical walls of a formfor casting a concrete slab in horizontal position comprising: means forsupporting a plurality of form sections to define a vertically enclosedvolume corresponding to the slab to be cast therein, said supportingmeans comprising a plurality of supports spaced about the perimeter ofthe form, each support including a horizontal base, a pair of verticallyextending angles on said base, said angles having oppositely directedlegs parallel to the outer surfaces of the form sections and outwardlyextending legs spaced apart to provide a vertically extending slottherebetween, and means permanently spanning said oppositely directedlegs and secured thereto to maintain the spacing between said outwardlyextending legs.

13. Structural supporting means for the narrow vertical walls of a formfor casting a concrete slab in horizontal position comprising: means forsupporting a plurality of form sections to define a vertically enclosedvolume corresponding to the slab to be cast therein, said supportingmeans comprising a plurality of supports spaced about the perimeter ofthe form, each support including a horizontal base, a pair of verticallyextending angles on said base, said angles having oppositely directedlegs parallel to the outer surfaces of the form sections and outwardlyextending legs spaced apart to means permanently spanning saidoppositely directed legs and secured thereto to maintain the spacingbetween said outwardly extending legs; and means pulling said formsections against said spanning means in supported relation.

14. Structual supporting means for the narrow vertical walls of a formfor casting concrete slab in horizontal position comprising: means forsupporting a plurality of form sections to define a vertically enclosedvolume corresponding to the slab to be cast therein, said supportingmeans comprising a plurality of supports spaced about the perimeter or"the form, each supporting including a horizontal base, a pair ofvertically extending angles on said based, said angles having oppositelydirected legs parallel to the outer surfaces of the form sections andoutwardly extending legs spaced apart to provide a vertically extendingslot therebetween; means spanning said oppositely directed legs andsecured thereto to maintain the spacing between said outwardly extendinglegs; means for supporting a plurality of second level from sectionsabove said first mentioned form to define a second level verticallyenclosed volume corresponding to a second level slab to be cast therein,said supporting means comprising a plurality of supports spaced aboutthe perimeter of the second level form in positions vertically above thelower level supports, each of said upper level supports including a pairof vertically extending angles having oppositely directed legs disposeddirectly above the oppositely extending legs of the lower supports andoutwardly extending legs disposed directly above the outwardly extendinglegs defining a vertically extending slot therebetween which is acontinuation of the vertically extending slot between the loweroutwardly extending legs; means connected to and spanning the oppositelydirected legs of the upper supports; and tie bars disposed in thevertically extending slot between said outwardly extending legs andconnected ot the outwardly extended legs of both the upper and lowersupports to tie the upper and lower form together.

References Cited by the Examiner UNITED STATES PATENTS 713,173 11/02Taylor 25--131 985,035 2/11 Hotchkiss 25-118 1,259,442 3/18 Ramm et al.25-131 1,535,584 4/25 Dorfman 25-121 1,549,607 8/25 Pulis 25-1311,988,900 1/35 Heltzel 25-118 2,640,249 6/ 53 Symons 25-131 2,688,7879/54 Lawler 25-118 2,924,850 2/ 60 Schultz 18-36 2,924,962 2/ 60 Nettle25--121 MICHAEL V. BRINDISI, Primary Examiner.

ROBERT F. WHITE, Examiner,

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Ne.3,182,948 Mey 11, 1965 Earnest Ralph Lawrence It 1e hereby certified meterrer eppeere in the abe-ve numbered petent requiring correction andthat the said Letters Patent should read as corrected below.

Column 5, line 2, for "lab" read slab column 8, line 13, after "to"insert provide a vertically extending slot therebetween, and line 25,for "supporting" read support Signed and sealed this 19th day of October1965.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer r Commissioner ofPatents

1. A FORM FOR CASTING A CONCRETE SLAB IN HORIZONTAL POSITION COMPRISING:A PLURALITY OF FORM SECTIONS; AND MEANS CONNECTING SAID SECTIONSTOGETHER IN SUBSTANTIALLY END-TOEND RELATION TO DEFINE A VERTICALLYENCLOSED VOLUME OF SMALL HEIGHT RELATIVE TO ITS HORIXONTAL DIMENSIONCORRESPONDING TO THE SLAP TO BE CAST THEREIN, SAID FORM SECTIONSINCLUDING CORNER END SECTIONS HAVING SUBSTANTIALLY CONTINUOUS VERTICALWALLS PROVIDING HORIZONTAL SLOTS IN SUBRUPTED VERTICAL WALLS PROVIDINGHORIZONTAL SLOTS IN SUBSTANTIALLY THE MID HOIRIZONTAL PLANE OF THE FORMFOR RECEIVING AND SUPPORTING THE ENDS OF SLAB REINFORCING RODS EXTENDINGIN THE PLANE OF THE SLAB BETWEEN SECTIONS AT OPPOSITE SIDES OF THE FORM.5. A FORM FOR CASTING A CONCRETE SLAB IN HORIZONTAL POSITION COMPRISING:A PLURALITY OF FORM SECTIONS; AND MEANS CONNECTING SAID SECTIONSTOGETHER IN SUBSTANTIALLY END-TO-END RELATION TO DEFINE A VERTICALLYENCLOSED VOLUME CORRESPONDING TO THE SLAP TO BE CAST THEREIN, SAIDCONNECTING MEANS COMPRISING HORIZONTAL BASE PLATES, SUPPORTS EXTENDINGVERTICALLY FROM SAID BASE PLATES, AND ATTACHMENT MEANS EXTENDINGTRANSVERSELY OF SAID VERTICAL SUPPORTS AND HAVING MEANS ADJACENT THEIROPPOSITE ENDS FOR ATTACHMENT TO THE ADJACENT ENDS OF SAID SECTIONS, SAIDVERTICAL SUPPORTS EACH COMPRISING A PAIR OF VERTICALLY EXTENDING ANGLESHAVING OPPOSITELY EXTENDING, INWARDLY FACING LEGS ON WHICH SAIDATTACHMENT MEANS ARE MOUNTED AND ADJACENT, OUTWARDLY EXTENDING LEGSSPACED APART TO PROVIDE A SLOT THEREBETWEEN FOR THE RECEPTION OF ANATTACHMENT TONGUE.